New England’s biggest utility has won approval for new charges on future solar customers starting next January — but in the process Eversource has angered some lawmakers with jurisdiction over its industry, including members of the Chelmsford’s delegation.

Vote Solar and Attorney General Maura Healey have both appealed the department’s approval of the new Eversource rates.

Mahony, who is Healey’s senior policy adviser for energy, suggested lawmakers should craft legislation that discourages customers from using electricity when demand on the grid is high. Demand fluctuates throughout the day as consumers turn on lights, flip on air conditioning and run electrical appliances. The demand charge in the Eversource rates does not vary based on time of day.

Sen. Michael Barrett, a Lexington Democrat and the Senate chairman of the committee, had a similar perspective to Mahony on the demand charges, questioning Eversource about why it wasn’t linked to when demand was highest on the grid as a whole.